Association of a polygenic risk score with risk of abnormal ultrasound findings and ovarian cancer in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

Abstract

10542 Background: Several susceptibility loci have been identified in genome-wide association studies (GWAS) of single nucleotide polymorphisms (SNPs) that are associated with ovarian cancers. Polygenic risk scores (PRS) combining certain loci have shown limited performance at predicting ovarian cancer risk. However, the utilization of PRS with ovarian cancer screening tests, like transvaginal ultrasound (TVU), warrants further evaluation. This study investigated the association between a polygenic risk score and ovarian cancer risk and abnormal TVU screening in a large-scale randomized controlled ovarian cancer screening trial. Methods: A polygenic risk score was constructed using weighted sums of risk alleles of 15 ovarian cancer SNPs identified in previous GWAS to evaluate the association with abnormal TVU screening results and ovarian cancer outcomes in female participants of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Complete genotyping information, TVU results, and ovarian cancer outcomes were available for 15722 females (mean age 62.2 years +/- 5.3) with European ancestry, including 116 ovarian cancer cases. Abnormal TVU was defined as ovarian volume or cyst volume > 10 cm3, any solid/cystic component within a cystic ovarian tumor, or any solid area or papillary projection extending into the cavity of a cystic ovarian tumor. Polygenic risk scores were categorized as quartiles and odds ratios (OR) were calculated to assess risk of ovarian cancer or abnormal TVU result using the lowest PRS quartile as reference category. Results: TVU screening results were abnormal for 732 (732/15722, 4.66%) participants and normal for 14990 (14990/15722, 95.3%) participants at trial baseline. PRS within the fourth quartile demonstrated increased risk of ovarian cancer with reference to the lowest quartile (OR 1.77, 95% confidence interval: 1.04-3.08). Similarly, women in the highest quartile of the PRS had increased odds of an abnormal TVU screening result (OR 1.46, 95% confidence interval: 1.17-1.83) compared to women in the lowest PRS quartile. Conclusions: A polygenic risk score including 15 loci previously shown to be associated with ovarian cancer risk showed an association with increased ovarian cancer risk in the PLCO trial. Furthermore, the PRS was also associated with abnormal ultrasound results. Our findings support further evaluation of polygenic risk scores and transvaginal ultrasound for ovarian cancer risk stratification and screening approaches.